This invention provides improvements in thickening or dewatering devices having particular advantage in application to pulp slurry. It will be so described, though obviously not so limited in application.
In the processing of pulp, fibrous particles are moved through various stages of refining in a liquid vechicle, presenting such particles, in most case, in a high volume, low consistency, slurry flow. In certain stages of refining the slurry must be of a higher consistency than in other stages. This necessitates periodic use of thickening apparatus. There have been many devices of the prior art directed to such purposes, such as vacuum filters which rotate, mechanical screen devices which are vibrated, and screw presses. These devices of the prior art are large in size so that they require considerable space for installation, they are expensive as far as capital investment is concerned and quite costly to operate. In addition to the foregoing disadvantages, their efficiency has been a matter of some concern. A prime area of concern in their use is that they do permit the escape of obnoxious or dangerous fumes.
There are inexpensive screening devices which can be used for dewatering or thickening purposes. However, these have been, in the main, either too large for a given capacity or basically incapable of handling a high volume slurry flow.
Accordingly, the prior art thickening apparatus for the purposes described have not been satisfactorily contrived so as to be able to handle a large flow volume in a minimal amount of space and at a low cost, both from a standpoint of capital investment and operation.